


Breathless

by SmolDargon



Series: Adventures in Anatomy [5]
Category: Undertale (Video Game)
Genre: Gen, Post-Undertale Pacifist Route, anatomical discussion, mild saucy humor
Language: English
Status: Completed
Published: 2021-02-02
Updated: 2021-02-02
Packaged: 2021-03-18 13:26:55
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,831
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29983530
Author URL: https://archiveofourown.org/users/SmolDargon/pseuds/SmolDargon
Summary: Beach days are great! Provided you can swim...
Series: Adventures in Anatomy [5]
Series URL: https://archiveofourown.org/series/2205429
Kudos: 3





	Breathless

It was a perfect day for a trip to the beach. While most of the monsters had been eager to join, it had taken a little persuasion to convince the Gaster brothers and the human to come along. Wingdings didn't like to leave projects undone, Sans was just downright lazy, and Papyrus seemed a bit self-conscious. The human was just as self-conscious, if not more so; she seemed downright apprehensive. Even so, Toriel and Frisk had finally gotten everyone loaded in a couple vehicles and on their way. On arrival, they were delighted to see the beach was completely empty. It seemed everyone else had better things to do than venture into the waves. Toriel and Wingdings set up chairs and towels to lounge on, while the rest of the group made a dash for the water. Everyone was having fun, it seemed: Undyne and Alphys had teamed up to battle Sans and Papyrus in a game of chicken, Frisk and Toriel were building a sandcastle, and Wingdings and the human had somehow managed to doze off under an umbrella.

Eventually, Alphys tagged out for a break, so Undyne invited the human to take her place in their game. It was hardly a fair fight; the human's thighs were built for clinging to half ton animals. It was no trouble to hang onto Undyne and shove Sans from his brother's shoulders. He chuckled and, in a small act of revenge, turned the human's soul blue and tossed her out into the deeper water.

They became concerned when she didn't immediately resurface. Papyrus strode out to retrieve her, becoming alarmed when he discovered her flailing uselessly just under the surface. It seemed the human's apprehension was born of an inability to swim. He drug her back onto the beach so she could catch her breath, while Sans followed, apologizing profusely. The human's coughing finally subsided and she was able to wave him off. She was fine, and he hadn't known she couldn't swim. Alphys determined that the human was alright, and they all decided to ensure she stayed in the shallows for the rest of the day.

"YOU HAVE BEEN COUGHING FOR A WHILE NOW, ARE YOU SURE YOU'RE ALRIGHT?", Papyrus inquired in a concerned tone. He had basically refused to leave her side while she recovered.

The human regarded him warmly, "I'm fine, Paps! Just need to catch my breath."

The skeleton eyed her dubiously.

"YOU'VE BEEN TRYING TO CATCH YOUR BREATH FOR TWENTY MINUTES."

"Well, I did just almost drown."

He narrowed his eyes.

"TOUCHE."

He paused for a moment, considering his words.

"HOW DOES THAT WORK, ANYWAY?"

The human raised a brow at him.

"How does what work?"

"YOU KNOW, THE WHOLE…DROWNING THING."

She gave him a confused look.

"Do….do skeletons not drown? Can you breathe underwater?"

"WE CAN! WE JUST ABSORB OXYGEN DIRECTLY THROUGH OUR SOULS, SINCE THEY'RE BASICALLY CONSTANTLY EXPOSED ANYWAY. WATER IS HARDER TO BREATHE IN THAN AIR, BUT THERE'S STILL OXYGEN, SO WE CAN STILL BREATHE. HOW DO HUMANS BREATHE IN THE WATER?"

"Oh, wow, um…", she thought for a moment before continuing, "Well, we basically have a pair of sacs in our chest that we use to hang onto air. We draw air in, a tube system in the sacs pulls oxygen out of the air, and then we release the non-oxygen…stuff."

"THAT SOUNDS MADE-UP."

"Everything is made-up, we've had this conversation before", she chuckled.

"YES, BUT THIS SOUNDS EVEN MORE MADE-UP."

"Alright, would it help if I gave you the in-depth explanation with proper terminology?"

Papyrus nodded, handing her a stick, "YES, PLEASE! HERE, USE THIS IF YOU NEED TO DRAW A DIAGRAM!"

The human took the stick, eyeing it distastefully.

"I'm…not the best artist. Don't judge me."

She shifted into a cross-legged position, drawing what appeared to be the outline of a human in the sand.

"IS THAT SUPPOSED TO BE YOU? IT NEEDS HAIR. AND A WORKOUT REGIMEN…"

She gently poked him in the ribcage with the stick.

"Hush, you."

She drew a line from the sand-human's mouth down its throat and a short distance into its chest. She drew two large, oval shapes in the chest, one on each side, and made the line split to intersect each oval. She didn't look too happy with her art, but shrugged, deciding it would suffice for her purposes. The average human would recognize it as the respiratory system, but she explained it for Papyrus.

"So, this is the mouth and nose, of course. They connect to the trachea--most people just call it the windpipe because they're not sophisticated enough for proper science--which connects to the lungs via these tubes, which are called bronchi. The bronchi actually branch off ever smaller into the lungs, and at the end they have these little bubble structures called alveoli."

She tried her best to illustrate the bronchioles and alveoli, but she was uncertain if they looked alright. She pressed on with the explanation anyway, Papyrus leaning over her shoulder.

"And underneath all of this is a muscle called the diaphragm," she drew a horizontal line under the bottom of the lungs.

"Basically, we suck air into the lungs, pull out the oxygen, and expel the other useless components. We actually use a pressure differential to breathe, which is pretty neat. The diaphragm tenses and pulls downward, creating a space of low air pressure in the lungs, causing air to rush in from the outside. To exhale, the diaphragm relaxes, and the air rushes back out into the now lower pressure outside."

She knew the skeleton's specialty was physics and engineering, so she looked to see if he was following so far. His rapt expression seemed to indicate he understood.

"When we inhale, the air gets conducted down the bronchi and into the alveoli. These guys are actually connected directly to our bloodstream. Here, the oxygen from the air moves into the bloodstream, while the carbon dioxide waste gas moves out of the blood and into the alveoli. Then, we exhale and release it all."

"MAKES SENSE. GASES MOVE TO AREAS OF LOWER CONCENTRATION, RIGHT?"

She nodded in the affirmative.

"Right. So, the biggest flaws in the system are its need for pressure differentials and its inability to process liquids. The whole pressure thing is fine, as long as we don't, oh I don't know, get stabbed or something. But the liquids thing… Well, you know how oxygen in the air tends to exist as two oxygen atoms bonded together, and water is just an oxygen bonded to two hydrogens?"

He nodded; chemistry wasn't really his forte, but this was something anyone should have a bare bones understanding of.

"Well, our lungs aren't able to extract that oxygen from the water molecule. And water, being a liquid, is harder to move around, especially since our lungs aren't designed to handle liquids. So, if we get too much water in our lungs, it keeps us from being able to pull in air to process."  
Papyrus nodded in understanding.

"THAT MAKES SENSE. I ASSUME THIS INHERENTLY FLAWED SYSTEM--ALONG WITH YOUR APPARENT INABILITY TO TREAD WATER--IS WHY YOU AVOID DEEP WATER?"

She nodded sadly.

"I've never been a particularly strong swimmer. Never took any classes or anything."

"WELL, IF IT MAKES YOU FEEL ANY BETTER, SKELETONS CAN'T SWIM EITHER."

She looked at him in surprise; how had he retrieved her from the water if he couldn't swim?

"WE'RE TOO DENSE; WE SINK! BUT SINCE WE CAN STILL BREATHE UNDERWATER, IT'S NOT NORMALLY AN ISSUE. WE CAN JUST WALK ON THE BOTTOM WHEREVER WE NEED TO GO. YOU WEREN'T IN TERRIBLY DEEP WATER, I JUST HAD TO JUMP A LITTLE TO CATCH YOU."

The human was still quite surprised Papyrus had beaten Undyne to the rescue. After all, she was literally a fish woman. He still looked a bit troubled. She figured he had more questions.

"SO…YOU MENTIONED SOMETHING ABOUT GETTING STABBED? AND THAT COULD CAUSE MORE PROBLEMS THAN JUST DAMAGE AND LEAKING?"

"Oh… yes. Stab and gunshot wounds--or really any wound that ruptures or pierces the chest cavity--can cause a couple of different problems. Sucking chest wounds are nasty, but you can usually patch a person up, literally, with tape until they get proper treatment. But those can occasionally progress and become worse."

He looked concerned.

"WHAT COULD BE WORSE THAN LEAKING AND BEING HURT?"

The human continued, deadpan, "Collapsed lungs."

The skeleton looked alarmed, so she continued her explanation.

"It's referred to as pneumothorax. It's what happens when the chest cavity gets a hole punched in it. The result is that the chest cavity becomes a high-pressure area, which causes the lung to just collapse. Ironically, the treatment is often to punch another hole in the chest. That way the pressure can level out. The possibility of collapsing the lungs is one of two reasons you never remove an object that's penetrated the body; it may very well be the only thing keeping the chest cavity sealed, and thus pressurized. The other reason is, of course, because the object may also be the only thing keeping the person from bleeding out. Only a doctor should remove any foreign object from an injury."

Papyrus looked thoughtful. It seemed there was still much to learn about humans. At least he didn't have to worry about the human's lung collapsing; he would just have to wait out her cough. She would probably be alright, anyway. She was tougher than he'd originally expected.

"GOOD TO KNOW… I HAVE ONE MORE QUESTION."

"Shoot."

"WHY DO HUMAN FEMALES HAVE BIGGER LUNGS THAN THE MALES?"

"Th--what?", the human stammered. She seemed at a loss.

"WELL, I THOUGHT THAT WAS WHY FEMALES HAD THE EXTRA CHEST TISSUE?"

She was quiet for a moment before realizing what exactly he was referring to. She proceeded to explode in a fit of alternating laughter and coughing.

Papyrus looked confused and concerned.

"WAS IT SOMETHING I SAID?"

With tears in her eyes, the human choked back a laugh and corrected her skeleton friend.

"Papyrus, _oh my god_ , those are just breasts! They're not even part of the breathing system!"

She seemed unable to stop laughing and, by extension, coughing.

"OH. WHAT ARE THEY FOR?"

She snorted, trying desperately to calm herself.

"They're just secondary sex characteristics! _Oh my god_ …. We use them to nurse our young, that's why only the females have them!"

She was fighting a losing battle with her laughter.

Papyrus seemed to realize the awkwardness of the situation.

"AH. WELL, FORGIVE ME FOR BEING NOSY."

The human wandered off to find some water, still trying to calm herself. Wingdings sat up from under the umbrella nearby, fixing a stern look on his brother.

"You Know Good And Well What Breasts Are, Papyrus", he signed, deadpan.

Papyrus just leered at his brother with a knowing smile.

"OF COURSE. I JUST WANTED TO SEE WHAT SHE WOULD DO."

**Author's Note:**

> Naive Papyrus? Not in my library.


End file.
